Simple question on Speed, F stop and Exposure
On the D7000 I am a little confused on how to manually set the speed and aperture and have a correct exposure. Maybe this is not possible.
I know on S - I select the speed - camera selects F stop.
I know on A - I select the f stop - camera selects the speed.
If I use M so I can select both the speed and F stop then I have no control over exposure, is this correct? As an example to get a sharp photo if I want to shoot a bird using a 300mm lens and I want to use a fast speed such as 1000 and I want to select an aperture such as F8 then how do I get a correct exposure?
I ask because I see recommendations that advise you to use a certain speed and aperture for the sharpest photo.
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#2. "RE: Simple question on Speed, F stop and Exposure" | In response to Reply # 0dm1dave Nikonian since 12th Sep 2006Sun 17-Apr-11 02:59 PM
If you are shooting in manual and you set specific shutter speed (1/1000s) and aperture (f/8) then you can raise or lower your ISO to get the proper exposure. You can also use auto ISO and let the camera set the ISO to get the correct exposure for your chosen shutter speed and aperture.
There may be times when the correct exposure just can not be made with the values that you prefer so you will have to either open up the aperture or slow down your shutter speed.
If you are shooting action, like sports or birds, a fast shutter speed is probably more important then aperture so shutter priority may be your best mode.
You would use aperture priority when depth of field is more important.
Hope this helps.
#3. "RE: Simple question on Speed, F stop and Exposure" | In response to Reply # 0gkaiseril Nikonian since 28th Oct 2005Sun 17-Apr-11 03:36 PM
Exposure starts the the EV,
The value is a single number. Based on that number and a known ISO (ASA or Din for film) of the recording media one can determine the combinations of shutter speed and aperture that will provide a correct or acceptable exposure.
If you set your ISO to a fixed value, turn Auto ISO off, then you will have control of your fstop and shutter speed with a consistent ratio between the 2 settings.
The relationships are fairly complex and is based on the law of squares, 10 to the 2 power, and the values for the ISO, fstop, and shutter speed are adjusted by this ratio.
See The Ultimate Exposure Computer or Understanding Exposure.
It is even possible when one understands the EV to set the camera to a close to prefect exposure without a light meter. Ever wonder how Ansel Adams or other photographers determined exposures before there were electric light meters?
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#4. "RE: Simple question on Speed, F stop and Exposure" | In response to Reply # 0Len Shepherd Nikonian since 09th Mar 2003Sun 17-Apr-11 05:01 PM
If you are asking how do you know if you have a shutter speed and aperture likely to give correct exposure it is fairly straightforward.
If you set any aperture and any shutter speed except "bulb" underneath the image in the viewfinder in yellow lettering there is the shutter speed followed by the aperture. Then there is a little scale of 0 for under exposure, . for correct exposure, and + for over exposure.
You adjust shutter speed and aperture until you get a single l under the . and you then have correct exposure.
Photography is a bit like archery. A technically better camera, lens or arrow may not hit the target as often as it could if the photographer or archer does not practice enough.
#5. "RE: Simple question on Speed, F stop and Exposure" | In response to Reply # 0ReadnFool Registered since 16th Jan 2011Mon 18-Apr-11 10:16 PM
Your exposure is determined by your Aperture, Shutter speed and ISO.
As you mentioned in A mode you pick the aperture and the camera finds the proper shutter speed for the ISO you have selected.
In mode S you choose the shutter speed and the camera chooses the aperture for the proper exposure at the ISO you have selected.
In manual you choose both the shutter speed and aperture. There is a little meter inside the view finder to help you. (in the other modes this meter tells you if you have set any exposure compensation, but in manual it functions as an exposure meter).
You may not be able to choose the exact combination and have the exposure be right if the light is wrong.
Remember that all three items work together. If you are at ISO 100, f4, and 1/60 and the exposure is right and you go to manual mode to tweak. If you want to go to 1/120 you either need to open your aperture by on stop to f2.8 or increase you ISO t0 200 to keep the exposure the same.
What typically happens is the light is not enough, you open the lens up as far as you can, and then to get the shutter speed down you dial up the ISO as high as you need to and deal with the noise in the picture from the high ISO.
Remember the effects of each setting:
Shutter speed freezes action or allows blur
Aperature affects depth of field (how much of the picture is in focus at the same time)
ISO effects the picture quality (noise and grain)
In shooting birds you probably don't want to sacrifice clarity of high shutter speed so you have to sacrifice some depth of field and / or picture quality to get the exposure.
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#6. "RE: Simple question on Speed, F stop and Exposure" | In response to Reply # 0billD80 Nikonian since 22nd Jan 2007Tue 19-Apr-11 10:08 AM
>I ask because I see recommendations that advise you to use a
>certain speed and aperture for the sharpest photo.
As people are saying, it's the available light that determines what you can do, and still have a "correct" exposure.
So, in M-Mode, you are just setting the f/stop and shutter speed according to what the camera meter is recommending. If, at ISO100, you have settings for 1/1000th and f/8, but the camera indicates this is really underexposed, then you must increase the ISO (thus increasing sensor sensitivity) to a value where your settings will be OK for proper exposure.
Keep in mind you can do this, and still remain in S or A modes. Let's say you really want to use f/6.3 in A-Mode, but the shutter speed will be 1/250th (too slow), then just up your ISO. Bear in mind that above ISO800 you may start to notice some "noise" in the image, depending on how large you view/print.
By staying in A or S modes, you can STILL arrive at the same values, but it will be much faster, and more accurate if you do any recompsng, panning, etc.
I use A-Mode for sports all the time, and with just a few test shots of where I'm shooting, I know how low I can set my ISO and still have the shutter-f/stop settings where I want them.
#7. "RE: Simple question on Speed, F stop and Exposure" | In response to Reply # 6b1234s Registered since 05th Dec 2010Tue 19-Apr-11 11:51 AM
"Keep in mind you can do this, and still remain in S or A modes. Let's say you really want to use f/6.3 in A-Mode, but the shutter speed will be 1/250th (too slow), then just up your ISO."
This is exactly what I wanted to do. Shoot in A mode but also make sure S is where I want it. I thought I could only achieve this in M mode but I tried as you suggested, changing the ISO and it worked great.
Things can be pretty simple when a knowledgeable person explains them.
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#9. "RE: Simple question on Speed, F stop and Exposure" | In response to Reply # 7billD80 Nikonian since 22nd Jan 2007Tue 19-Apr-11 05:56 PM
>This is exactly what I wanted to do. Shoot in A mode but also
>make sure S is where I want it. I thought I could only achieve
>this in M mode but I tried as you suggested, changing the ISO
>and it worked great.
>Things can be pretty simple when a knowledgeable person
You're welcome. Truth be told, I almost ALWAYS use Aperture priority, because it can be adapted to almost any situation, landscape to action.
#8. "RE: Simple question on Speed, F stop and Exposure" | In response to Reply # 0
To be able to choose BOTH your aperture and shutter speed, you'll need to be in camera manual and adjust your ISO to get a zeroed out exposure reading in your viewfinder as Len has described. An alternative is to use your cameras' excellent Auto ISO feature. Now your ISO floats (much as the ss does when in Aperture priority) to give you what the camera thinks is a good exposure. You can still dial in exposure compensation via top right EC button if necessary.
I use this approach routinely and find it gives great flexibility. As the light changes or the situation warrants, I can dial in more or less speed or modify the aperture, knowing that the ISO will be changed appropriately. So for instance if I'm shooting birds in flight at 1/2000 and f8 and see an interesting subject in deep shadow I can quickly shift to 1/250 at f4. With a fixed ISO you would likely have to change the ISO as well instead of having the camera do it for you.